Additionally, version strings can have an epoch value
defined that will overrule any version comparison, unless the epoch values
are equal. This is specified in an epoch:version-rel format. For example,
2:1.0-1 is always greater than 1:3.6-1.

Keep in mind that the pkgrel is only compared if it is
available on both versions given to this tool. For example, comparing 1.5-1
and 1.5 will yield 0; comparing 1.5-1 and 1.5-2 will yield < 0 as
expected. This is mainly for supporting versioned dependencies that do not
include the pkgrel.